In the early days of the personal computer, browsing or editing a document was difficult to do. The document would often take up several screens worth of information, and it was difficult for the user to find specific sections of the document. The user would often have to scroll through an entire document screen by screen by pressing function keys assigned to a "scroll up" and "scroll down" function in an often futile attempt to find a specific section. This was slow and cumbersome, and resulted in many users printing off the entire document instead of trying to view it on the display. This was a waste of valuable natural resources, and was a giant step backwards in the often expressed goal of reaching a paperless office.
Some early editors attempted to partially solve this problem by providing a "search" or "find" function. While somewhat helpful, these functions depended on a user knowing a specific (and reasonably unique) word or string of words that is contained in the specific section he is looking for. This approach often turned into a guessing game for a user, and often resulted in the user again giving up and printing off the entire document. In addition, many users simply did not know (or couldn't remember) any specific word or string of words in the section they were looking for.
It was thought that problems like the above would be solved by a great panacea called a "graphical user interface", first introduced to the market by Apple, and later adopted by Microsoft with its "Windows" program and by IBM with OS/2 and Presentation Manager. One common feature of these graphical interface programs is a scroll bar. A scroll bar is commonly associated with a display window, and is most useful when only a small portion of a document can be displayed in a display window at any one time. The scroll bar contains what is known as a "slider". The slider's relative position in the scroll bar graphically indicates the relative position of the entire document that is currently displayed in the display window. One scroll bar is often used to indicate relative vertical position, while a second scroll bar can be used to indicate relative horizontal position.
A scroll bar is normally used in conjunction with an input device such as a mouse, track ball, or light pen. When a user wants to move to a different section of a document, he can either move the mouse cursor to a new position on the scroll bar (click operation), or can place the mouse cursor on the slider, press and hold one of the mouse buttons, and move the mouse cursor either one side or the other of the slider (drag operation). While both of these operations are helpful in rapidly moving from one section of a document to another section, they don't do much to help a user find the specific section of the document he is looking for.
Some techniques are known in the art to enhance the operation of a scroll bar to make it easier for a user to find a specific section he is looking for. One such technique is described in pending patent application Ser. No. 07/531,213, filed on May 31, 1990 by the assignee of this invention and entitled "Scrollbar Having System or User Provided Information". This application discloses displaying indicia such as alphanumeric symbols within a scroll bar to assist a user find a specific section in a document. For example, if the document contained in the window was a dictionary, the scroll bar disclosed in this application could contain some or all of the letters "A" through "Z". If the user wanted to look up a specific word that started with "P", for example, he could simply move the mouse cursor to the "P" portion of the scroll bar and click on the mouse button. While this technique is very useful in making it easier to find a specific section in a document, it is quite complex and highly dependent on the contents of the document itself, since different documents would require that different indicia be displayed in the scroll bar to be useful. In addition, documents such as image or data files are not organized in a manner that would allow this technique to be used.
Another technique for enhancing the operation of a scroll bar is described in pending patent application Ser. No. 07/619,628, filed on Nov. 28, 1990 by the assignee of this invention and entitled "Graphical Method of Indicating the Position of and Performing an Operation on a Plurality of Selected Objects in a Computer System". This application discloses placing a marker icon in a scroll bar when an object in a window is selected. This technique makes it easier for a user to quickly scan previously visited areas of a document. While helpful, this technique loses much of its effectiveness if multiple areas of a document are selected, since the scroll bar quickly fills up with marker icons that have less and less meaning. In addition, this technique contains no indication as to when, how long, or how often a specific area of the document has been viewed.